As measures which enable a vehicle to make emergency running to a repair shop such as a gas station when a pneumatic tire is punctured while the vehicle is running, there are a case of causing a tire to have a special structure so as to embed highly rigid rubber into sidewall portions of the pneumatic tire, and a case of causing a tire/wheel assembly to have a special structure so as to insert a core (run-flat support body) into a cavity portion of the pneumatic tire mounted on a rim of a wheel while keeping the conventional tire structure. Out of the two cases, the latter mode proposal (for example, refer to Patent Documents 1 and 2) is on a tire/wheel assembly. In the case of this tire/wheel assembly, a run-flat support body is composed of an annular shell whose cross-section in the width direction of the tire bifurcates and has right and left leg portions. The two leg portions of the annular shell are mounted on rim seats respectively with an elastic ring attached to each of the two leg portions. Thereby, the run-flat support body supports the inner peripheral surface of the tire.
The above-described run-flat support body has an advantage that conventional wheel/rim constructions can be used as they are without any substantial modification made thereto. However, weight of the annular shell is heavy since the annular shell is usually formed of a metal material, causing a deterioration of a fuel consumption rate when the vehicle makes normal running.
[Patent Document 1] Japanese patent application Kokai publication No. Hei 10-297226
[Patent Document 2] Japanese patent application Kokai publication No. 2001-519279